U.S. patent application number 14/333700 was filed with the patent office on 2016-01-21 for camera network and method of operating thereof.
The applicant listed for this patent is EYEDEAS Ltd.. Invention is credited to Fan ZHANG.
Application Number | 20160021292 14/333700 |
Document ID | / |
Family ID | 55075650 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160021292 |
Kind Code |
A1 |
ZHANG; Fan |
January 21, 2016 |
Camera Network And Method Of Operating Thereof
Abstract
A method for operating a camera network having a plurality of
cameras, comprising the steps of: communicating with the plurality
of cameras to determine one or more operation parameters for each
of the plurality of cameras; synchronizing the one or more
operation parameters for each of the plurality of cameras; and
coordinating a capture of multimedia data using the plurality of
cameras with the one or more synchronized operation parameters.
Inventors: |
ZHANG; Fan; (Sheung Wan,
HK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EYEDEAS Ltd. |
Sheung Wan |
|
HK |
|
|
Family ID: |
55075650 |
Appl. No.: |
14/333700 |
Filed: |
July 17, 2014 |
Current U.S.
Class: |
348/211.2 |
Current CPC
Class: |
H04N 5/247 20130101;
H04N 5/23206 20130101; H04N 5/06 20130101 |
International
Class: |
H04N 5/232 20060101
H04N005/232; H04N 5/247 20060101 H04N005/247; H04N 5/06 20060101
H04N005/06 |
Claims
1. A method for operating a camera network having a plurality of
cameras, comprising the steps of: communicating with the plurality
of cameras to determine one or more operation parameters for each
of the plurality of cameras; synchronizing the one or more
operation parameters for each of the plurality of cameras; and
coordinating a capture of multimedia data using the plurality of
cameras with the one or more synchronized operation parameters.
2. A method in accordance with claim 1, wherein the step of
communicating with the plurality of cameras includes facilitating
communication with or between each of the plurality of cameras.
3. A method in accordance with claim 2, wherein the one or more
operation parameters for each of the plurality of cameras are
arranged to be synchronized to the one or more operation parameters
of one of the plurality of cameras.
4. A method in accordance with claim 3, wherein the one or more
operation parameters include a time base and/or a frame rate.
5. A method in accordance with claim 4, wherein communicating with
the plurality of cameras to determine a time base for each of the
plurality of cameras comprises the steps of: transmitting at least
one communication signal to each of the plurality of cameras; and
receiving at least one corresponding response signal from each of
the plurality of cameras.
6. A method in accordance with claim 5, wherein synchronizing the
time base of the plurality of cameras to the time base of the one
of the plurality of cameras comprises the steps of: determining at
least one transmission time difference for each of the plurality of
camera based on a difference between a transmission time of the
communication signal and a receiving time of the corresponding
response signal; determining an averaged transmission time
difference for each of the plurality of cameras based on the at
least one transmission time differences determined for each of the
plurality of cameras; and adjusting a clock time of each of the
plurality of cameras based on the at least one determined
transmission time difference such that the time base of each of the
plurality of cameras is synchronized to the time base of the one of
the plurality of cameras.
7. A method in accordance with claim 6, wherein the synchronization
of the frame rate for each of the plurality of cameras comprises
minimizing the frame offset among the plurality of cameras in the
camera network to be within a predetermined threshold or to be
substantially zero.
8. A method in accordance with claim 7, wherein communicating with
the plurality of cameras to determine a frame rate of each camera
comprises the steps of: transmitting a frame start signal to each
of the plurality of cameras upon each frame initiation at the one
of the plurality of cameras; and determining a frame time
difference at each of the plurality of cameras based on a time
difference between at least two consecutive frame start signals
received.
9. A method in accordance with claim 8, wherein synchronizing the
frame rate for each of the plurality of cameras includes: comparing
the determined frame time difference between at least two
consecutive frame start signals received with a frame time
difference of each of the plurality of cameras; and maintaining the
frame time difference of each of the plurality of cameras to be
within a predetermined range so as to substantially conform to the
frame time difference of the one of the plurality of cameras.
10. A method in accordance with claim 9, wherein maintaining the
frame time difference of each of the plurality of cameras to be
within a predetermined range includes: adjusting a frame rate of
the cameras of which the frame time difference is beyond the
predetermined range by altering the frame time difference of the
respective camera such that the frame offset of the plurality of
cameras is minimized to be within a predetermined threshold or to
be substantially zero.
11. A method in accordance with claim 10, wherein the step of
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate includes:
transmitting a targeted initiation time to each of the plurality of
cameras; and initializing the capture of multimedia data using the
plurality of cameras at the same targeted initiation time.
12. A method in accordance with claim 11, wherein the step of
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate further
includes: dynamically adjusting the time base and the frame rate of
the plurality of cameras when the plurality of cameras are
capturing multimedia data such that the time base of the plurality
of cameras remain synchronized and the frame offset among the
cameras is minimized to be within a predetermined threshold or to
be substantially zero during operation.
13. A method in accordance with claim 12, wherein the step of
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate includes:
detecting a triggering event for triggering the initiation of the
capturing of multimedia data; transmitting an initialization
command to each of the plurality of cameras; and initializing the
obtaining of multimedia data using the plurality of cameras in
response to the triggering event; wherein detection of the
triggering event includes detection of a tactile signal, an
infrared signal, an electromagnetic signal, a light signal, or an
audible signal.
14. A method in accordance with claim 1, wherein the multimedia
data includes image, video or sound.
15. A method in accordance with claim 1, wherein the communication
with or among the plurality of cameras is performed over a wireless
communication link.
16. A method in accordance with claim 15, wherein the plurality of
cameras are digital cameras each coupled with a communication
module for enabling wireless communication.
17. A system for operating a camera network having a plurality of
cameras, comprising: means for communicating with the plurality of
cameras to determine one or more operation parameters for each of
the plurality of cameras; means for synchronizing the one or more
operation parameters for each of the plurality of cameras; and
means for coordinating a capture of multimedia data using the
plurality of cameras with the one or more synchronized operation
parameters.
18. A system in accordance with claim 17, wherein the means for
communicating with the plurality of cameras is arranged to
facilitate communication with or between each of the plurality of
cameras.
19. A system in accordance with claim 18, wherein the one or more
operation parameters for each of the plurality of cameras are
arranged to be synchronized to the one or more operation parameters
of one of the plurality of cameras; and wherein the one or more
operation parameters includes a time base and/or a frame rate.
20. A system in accordance with claim 19, wherein the means for
communicating with the plurality of cameras to determine a time
base for each of the plurality of cameras is arranged to: transmit
at least one communication signal to each of the plurality of
cameras; and receive at least one corresponding response signal
from each of the plurality of cameras.
21. A system in accordance with claim 20, wherein the means for
synchronizing the time base of the plurality of cameras to the time
base of the one of the plurality of cameras is arranged to:
determine at least one transmission time difference for each of the
plurality of camera based on a difference between a transmission
time of the communication signal and a receiving time of the
corresponding response signal; determine an averaged transmission
time difference for each of the plurality of cameras based on the
at least one transmission time differences determined for each of
the plurality of cameras; and adjust a clock time of each of the
plurality of cameras based on the at least one determined
transmission time difference such that the time base of each of the
plurality of cameras is synchronized to the time base of the one of
the plurality of cameras.
22. A system in accordance with claim 21, wherein the means for
synchronizing the frame rate for each of the plurality of cameras
is arranged to minimize the frame offset among the plurality of
cameras in the camera network to be within a predetermined
threshold or to be substantially zero.
23. A system in accordance with claim 22, wherein the means for
communicating with the plurality of cameras to determine a frame
rate of each camera is arranged to: transmit a frame start signal
to each of the plurality of cameras upon each frame initiation at
the one of the plurality of cameras; and determine a frame time
difference at each of the plurality of cameras based on a time
difference between at least two consecutive frame start signals
received.
24. A system in accordance with claim 23, wherein the means for
synchronizing the frame rate for each of the plurality of cameras
is arranged to: compare the determined frame time difference
between at least two consecutive frame start signals received with
a frame time difference of each of the plurality of cameras;
maintain the frame time difference of each of the plurality of
cameras to be within a predetermined range so as to substantially
conform to the frame time difference of the one of the plurality of
cameras; and adjust a frame rate of the cameras of which the frame
time difference is beyond the predetermined range by altering the
frame time difference of the respective camera such that the frame
offset of the plurality of cameras is minimized to be within a
predetermined threshold or to be substantially zero.
25. A system in accordance with claim 24, wherein the means for
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate is arranged to:
transmit a targeted initiation time to each of the plurality of
cameras; initialize the capture of multimedia data using the
plurality of cameras at the same targeted initiation time; and
dynamically adjust the time base and the frame rate of the
plurality of cameras when the plurality of cameras are capturing
multimedia data such that the time base of the plurality of cameras
remain synchronized and the frame offset among the cameras is
minimized to be within a predetermined threshold or to be
substantially zero during operation.
26. A system in accordance with claim 25, wherein the means for
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate is arranged to:
detect a triggering event for triggering the initiation of the
capturing of multimedia data; transmit an initialization command to
each of the plurality of cameras; and initialize the obtaining of
multimedia data using the plurality of cameras in response to the
triggering event; and wherein detection of the triggering event
includes detection of a tactile signal, an infrared signal, an
electromagnetic signal, a light signal, or an audible signal.
27. A system in accordance with claim 17, wherein the communication
with or among the plurality of cameras is performed over a wireless
communication link.
28. A system in accordance with claim 27, wherein the plurality of
cameras are digital cameras, each coupled with a communication
module for enabling wireless communication.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of operating a
camera network with a number of cameras and particularly, although
not exclusively, to a method for controlling and synchronizing the
operation of a number of cameras in a camera network.
BACKGROUND
[0002] Cameras are optical instruments used for capturing still or
moving images (and/or sound). Generally, cameras can be classified
into two main categories, a point and shoot (P&S) type and a
single lens reflex (SLR) type. Both of these types are now
predominantly digital, but they may also use film to record an
image.
[0003] P&S type cameras have all the optical and/or electrical
instruments arranged in the camera body and the operation of
P&S type camera is largely automatic. Users of P&S cameras
can readily capture images by pointing the camera to the object or
image to be captured and actuating the shutter. Thus, P&S
cameras are simpler for use and are relatively small in size and
more compact.
[0004] SLR type cameras, on the other hand, allow a larger degree
of user manipulation as the lens of these cameras is readily
changeable. Users of SLR cameras will often have to manipulate the
optical and/or electrical instruments of the cameras before
capturing an image. Thus, the quality of images taken using SLR
cameras will often depend on the photographic skills of the user.
Also, SLR cameras are relatively large and more bulky compared with
P&S cameras.
[0005] Nonetheless, in some photographic (photo or video)
applications, it may be necessary to capture still or moving images
using different cameras at the same time. However, different types
of cameras (or different varieties of cameras of the same type)
will often have different operation characteristics. This presents
a significant challenge for realizing real time
synchronous/synchronized photographic (photo or video) shooting
with a plurality of cameras of different types.
SUMMARY OF THE INVENTION
[0006] In accordance with a first aspect of the present invention,
there is provided a method for operating a camera network having a
plurality of cameras, comprising the steps of: communicating with
the plurality of cameras to determine one or more operation
parameters for each of the plurality of cameras; synchronizing the
one or more operation parameters for each of the plurality of
cameras; and coordinating a capture of multimedia data using the
plurality of cameras with the one or more synchronized operation
parameters.
[0007] In one embodiment of the first aspect, the step of
communicating with the plurality of cameras includes facilitating
communication with or between each of the plurality of cameras.
[0008] In one embodiment of the first aspect, the one or more
operation parameters for each of the plurality of cameras are
arranged to be synchronized to the one or more operation parameters
of one of the plurality of cameras.
[0009] In one embodiment of the first aspect, the one or more
operation parameters include a time base and/or a frame rate.
[0010] In one embodiment of the first aspect, communicating with
the plurality of cameras to determine a time base for each of the
plurality of cameras comprises the steps of: transmitting at least
one communication signal to each of the plurality of cameras; and
receiving at least one corresponding response signal from each of
the plurality of cameras.
[0011] In one embodiment of the first aspect, synchronizing the
time base of the plurality of cameras to the time base of the one
of the plurality of cameras comprises the steps of: determining a
transmission time difference for each of the plurality of camera
based on a difference between a transmission time of the
communication signal and a receiving time of the corresponding
response signal; and adjusting a clock time of each of the
plurality of cameras based on the determined transmission time
difference such that the time base of each of the plurality of
cameras is synchronized to the time base of the one of the
plurality of cameras.
[0012] In one embodiment of the first aspect, synchronizing the
time base of the plurality of cameras to the time base of the one
of the plurality of cameras comprises the steps of: determining a
plurality of transmission time difference for each of the plurality
of camera, wherein each of the plurality of transmission time
difference for each of the plurality of camera is determined based
on a difference between a transmission time of the communication
signal and a receiving time of the corresponding response signal;
determining an averaged transmission time difference for each of
the plurality of cameras based on the plurality of transmission
time differences determined for each of the plurality of cameras;
and adjusting a clock time of each of the plurality of cameras
based on the determined averaged transmission time difference such
that the time base of each of the plurality of cameras is
synchronized to the time base of the one of the plurality of
cameras.
[0013] In one embodiment of the first aspect, the synchronization
of the frame rate for each of the plurality of cameras comprises
minimizing the frame offset among the plurality of cameras in the
camera network to be within a predetermined threshold or to be
substantially zero.
[0014] In one embodiment of the first aspect, communicating with
the plurality of cameras to determine a frame rate of each camera
comprises the steps of: transmitting a frame start signal to each
of the plurality of cameras upon each frame initiation at the one
of the plurality of cameras; and determining a frame time
difference at each of the plurality of cameras based on a time
difference between at least two consecutive frame start signals
received.
[0015] In one embodiment of the first aspect, synchronizing the
frame rate for each of the plurality of cameras includes: comparing
the determined frame time difference between at least two
consecutive frame start signals received with a frame time
difference of each of the plurality of cameras; and maintaining the
frame time difference of each of the plurality of cameras to be
within a predetermined range so as to substantially conform to the
frame time difference of the one of the plurality of cameras.
[0016] In one embodiment of the first aspect, maintaining the frame
time difference of each of the plurality of cameras to be within a
predetermined range includes: adjusting a frame rate of the cameras
of which the frame time difference is beyond the predetermined
range by altering the frame time difference of the respective
camera such that the frame offset of the plurality of cameras is
minimized to be within a predetermined threshold or to be
substantially zero.
[0017] In one embodiment of the first aspect, the step of
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate includes:
transmitting a targeted initiation time to each of the plurality of
cameras; and initializing the capture of multimedia data using the
plurality of cameras at the same targeted initiation time.
[0018] In one embodiment of the first aspect, the step of
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate further
includes: dynamically adjusting the time base and the frame rate of
the plurality of cameras when the plurality of cameras are
capturing multimedia data such that the time base of the plurality
of cameras remain synchronized and the frame offset among the
cameras is minimized to be within a predetermined threshold or to
be substantially zero during operation.
[0019] In one embodiment of the first aspect, the step of
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate includes:
detecting a triggering event for triggering the initiation of the
capturing of multimedia data; transmitting an initialization
command to each of the plurality of cameras; and initializing the
obtaining of multimedia data using the plurality of cameras in
response to the triggering event.
[0020] In one embodiment of the first aspect, detection of the
triggering event includes detection of a tactile signal, an
infrared signal, an electromagnetic signal, a light signal, or an
audible signal.
[0021] In one embodiment of the first aspect, the multimedia data
includes image, video or sound.
[0022] In one embodiment of the first aspect, the communication
with or among the plurality of cameras is performed over a wireless
communication link.
[0023] In one embodiment of the first aspect, the wireless
communication link is a WiFi or Bluetooth communication link, or
other wireless communication links.
[0024] In one embodiment of the first aspect, the plurality of
cameras are digital cameras each coupled with a communication
module for enabling wireless communication.
[0025] In accordance with a second aspect of the present invention,
there is provided a system for operating a camera network having a
plurality of cameras, comprising: means for communicating with the
plurality of cameras to determine one or more operation parameters
for each of the plurality of cameras; means for synchronizing the
one or more operation parameters for each of the plurality of
cameras; and means for coordinating a capture of multimedia data
using the plurality of cameras with the one or more synchronized
operation parameters.
[0026] In one embodiment of the second aspect, the means for
communicating with the plurality of cameras is arranged to
facilitate communication with or between each of the plurality of
cameras.
[0027] In one embodiment of the second aspect, the one or more
operation parameters for each of the plurality of cameras are
arranged to be synchronized to the one or more operation parameters
of one of the plurality of cameras.
[0028] In one embodiment of the second aspect, the one or more
operation parameters include a time base and/or a frame rate.
[0029] In one embodiment of the second aspect, the means for
communicating with the plurality of cameras to determine a time
base for each of the plurality of cameras is arranged to: transmit
at least one communication signal to each of the plurality of
cameras; and receive at least one corresponding response signal
from each of the plurality of cameras.
[0030] In one embodiment of the second aspect, the means for
synchronizing the time base of the plurality of cameras to the time
base of the one of the plurality of cameras is arranged to:
determine a transmission time difference for each of the plurality
of camera based on a difference between a transmission time of the
communication signal and a receiving time of the corresponding
response signal; and adjust a clock time of each of the plurality
of cameras based on the determined transmission time difference
such that the time base of each of the plurality of cameras is
synchronized to the time base of the one of the plurality of
cameras.
[0031] In one embodiment of the second aspect, the means for
synchronizing the time base of the plurality of cameras to the time
base of the one of the plurality of cameras is arranged to:
determine a plurality of transmission time difference for each of
the plurality of camera, wherein each of the plurality of
transmission time difference for each of the plurality of camera is
determined based on a difference between a transmission time of the
communication signal and a receiving time of the corresponding
response signal; determine an averaged transmission time difference
for each of the plurality of cameras based on the plurality of
transmission time differences determined for each of the plurality
of cameras; and adjust a clock time of each of the plurality of
cameras based on the determined averaged transmission time
difference such that the time base of each of the plurality of
cameras is synchronized to the time base of the one of the
plurality of cameras.
[0032] In one embodiment of the second aspect, the means for
synchronizing the frame rate for each of the plurality of cameras
is arranged to minimize the frame offset among the plurality of
cameras in the camera network to be within a predetermined
threshold or to be substantially zero.
[0033] In one embodiment of the second aspect, the means for
communicating with the plurality of cameras to determine a frame
rate of each camera is arranged to: transmit a frame start signal
to each of the plurality of cameras upon each frame initiation at
the one of the plurality of cameras; and determine a frame time
difference at each of the plurality of cameras based on a time
difference between at least two consecutive frame start signals
received.
[0034] In one embodiment of the second aspect, the means for
synchronizing the frame rate for each of the plurality of cameras
is arranged to: compare the determined frame time difference
between at least two consecutive frame start signals received with
a frame time difference of each of the plurality of cameras; and
maintain the frame time difference of each of the plurality of
cameras to be within a predetermined range so as to substantially
conform to the frame time difference of the one of the plurality of
cameras.
[0035] In one embodiment of the second aspect, the means for
synchronizing the frame rate for each of the plurality of cameras
is further arranged to: adjusting a frame rate of the cameras of
which the frame time difference is beyond the predetermined range
by altering the frame time difference of the respective camera such
that the frame offset of the plurality of cameras is minimized to
be within a predetermined threshold or to be substantially
zero.
[0036] In one embodiment of the second aspect, the means for
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate is arranged to:
transmit a targeted initiation time to each of the plurality of
cameras; and initialize the capture of multimedia data using the
plurality of cameras at the same targeted initiation time.
[0037] In one embodiment of the second aspect, the means for
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate is arranged to:
dynamically adjust the time base and the frame rate of the
plurality of cameras when the plurality of cameras are capturing
multimedia data such that the time base and the frame rate of the
plurality of cameras remain synchronized during operation.
[0038] In one embodiment of the second aspect, the means for
coordinating the capture of multimedia data using the plurality of
cameras with synchronized time base and frame rate is arranged to:
detect a triggering event for triggering the initiation of the
capturing of multimedia data; transmit an initialization command to
each of the plurality of cameras; and initialize the obtaining of
multimedia data using the plurality of cameras in response to the
triggering event.
[0039] In one embodiment of the second aspect, detection of the
triggering event includes detection of a tactile signal, an
infrared signal, an electromagnetic signal, a light signal, or an
audible signal.
[0040] In one embodiment of the second aspect, the multimedia data
includes image, video or sound.
[0041] In one embodiment of the second aspect, the communication
with or among the plurality of cameras is performed over a wireless
communication link.
[0042] In one embodiment of the second aspect, the wireless
communication link is a WiFi or Bluetooth communication link, or
other wireless communication links.
[0043] In one embodiment of the second aspect, the plurality of
cameras are digital cameras each coupled with a communication
module for enabling wireless communication.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Embodiments of the present invention will now be described,
by way of example, with reference to the accompanying drawings in
which:
[0045] FIG. 1A is a camera network with a number of cameras and a
controller in accordance with one embodiment of the present
invention;
[0046] FIG. 1B is a camera network with a number of cameras and a
controller in accordance with another embodiment of the present
invention;
[0047] FIG. 1C is a camera network with a number of cameras in
accordance with yet another embodiment of the present
invention;
[0048] FIG. 2 is a block diagram showing the key functional modules
of a camera in the camera network of FIG. 1A, 1B or 1C;
[0049] FIG. 3 is a block diagram showing the key functional modules
of a controller in the camera network of FIG. 1A, 1B or 1C;
[0050] FIG. 4 shows a flow diagram illustrating the basic operation
of the camera network of FIG. 1A, 1B or 1C;
[0051] FIG. 5A illustrates a time base synchronization process
between the controller and the camera in the camera network of FIG.
1A;
[0052] FIG. 5B illustrates a time base synchronization process
between two cameras in the camera network of FIG. 1B or 1C;
[0053] FIG. 6 shows a flow diagram illustrating the steps of
performing time base synchronization in accordance with one
embodiment of the present invention;
[0054] FIG. 7A illustrates a frame rate adjustment and
synchronization process between the controller and the camera in
the camera network of FIG. 1A;
[0055] FIG. 7B illustrates a frame rate adjustment and
synchronization process between two cameras in the camera network
of FIG. 1B or 1C;
[0056] FIG. 8 shows a flow diagram illustrating the steps of
performing frame rate adjustment and synchronization in accordance
with one embodiment of the present invention;
[0057] FIG. 9A illustrates a coordination process for capturing
multimedia data using a number of cameras (controlled by a
controller) in the camera network of FIG. 1A;
[0058] FIG. 9B illustrates a coordination process for capturing
multimedia data using a number of cameras (controlled by a
`master`) in accordance with one embodiment of the present
invention; and
[0059] FIG. 10 shows a flow diagram illustrating the steps of
coordinating the capturing of multimedia data using a number of
cameras in accordance with one embodiment of the present
invention;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0060] FIG. 1A shows a camera network 100A with a number of cameras
102A, 104A, 106A in accordance with one embodiment of the present
invention. In this embodiment, the camera network 100A includes
three cameras 102A, 104A, 106A and one controller 108A. The cameras
102A, 104A, 106A in the camera system 100A, which may have their
operation characteristics/parameters originally out of
synchronization due to the differences caused by their internal
components such as the clock crystals, are arranged to capture
still or moving images (and/or sound) simultaneously in a
synchronized manner using the method provided in the present
invention. Each of the cameras 102A, 104A, 106A is equipped with
necessary optical and electrical components for capturing still or
moving images and/or sound. As shown in FIG. 1A, each camera 102A,
104A, 106A is further coupled with an electronic module 112A, 114A,
116A having at least one communication means for enabling
communication with other cameras (or their associated electronic
modules 112A, 114A, 116A) and the controller in the camera network
100A through a wireless communication network 110A. The cameras
102A, 104A, 106A may be coupled with the electronic modules 112A,
114A, 116A through preferably a wired connection, or alternatively,
a wireless connection.
[0061] The controller 108A in the camera system of FIG. 1A is
arranged to communicate with each of the cameras 102A, 104A, 106A
(or their associated electronic modules 112A, 114A, 116A) in the
camera network 100A so as to synchronize the time base and/or the
frame rate and reduce the frame offset (difference between frame
start times of different cameras) of the cameras to realize
simultaneous synchronized operation of the cameras in the camera
network 100A. In the present embodiment, the synchronization of the
time base refers to the minimization of differences in the time
base of different cameras 102A, 104A, 106A in the camera system
100A. On the other hand, the reduction in frame offset among the
cameras 102A, 104A, 106A in the camera system 100A is realized by a
continuous adjustment of the frame rate of each of the cameras.
Preferably, an administrator of the camera network 100A can control
the activation, synchronization and operation of the cameras 102A,
104A, 106A in the camera network 100A through the controller 108A.
In one embodiment, the time base of each of the cameras 102A, 104A,
106A are synchronized to a time base set in the controller 108A.
Also, the frame offset among the cameras 102A, 104A, 106A and the
controller 108A is minimized by adjustment of the frame rates of
the cameras 102A, 104A, 106A. Alternatively, the controller 108A
may use the time base and frame rate from one of the cameras, say
camera 102A, as reference and adjusts the time base and frame rate
of the other cameras 104A, 106A in the camera network 100A to that
of the reference so as to synchronize the time base and minimize
the frame offset of the cameras 102A, 104A, 106A in the camera
network 100A.
[0062] In FIG. 1A, the cameras 102A, 104A, 106A and the controller
108A are in communication each other through a wireless
communication network 110A. Preferably, the wireless communication
network 110A utilizes wireless communication links such as WiFi,
Bluetooth, communication links 120A. Other electromagnetic or
optical communication signals may also be used as communication
links in some other embodiments.
[0063] FIG. 1B shows another camera network 100B in accordance with
one embodiment of the present invention. In this embodiment, the
camera network 100B includes three cameras 102B, 104B, 106B and one
controller 108B. The cameras 102B, 104B, 106B in the camera system
100B, which may have their operation characteristics/parameters
originally out of synchronization due to the differences caused by
their internal components such as the clock, are arranged to
capture still or moving images (and/or sound) simultaneously in a
synchronized manner using the method provided in the present
invention. Each of the cameras 102B, 104B, 106B is equipped with
necessary optical and electrical components for capturing still or
moving images and/or sound. As shown in FIG. 1B, each camera 102B,
104B, 106B is further coupled with an electronic module 112B, 114B,
116B having at least one communication means for enabling
communication with other cameras 102B, 104B, 106B (or their
associated electronic modules 112B, 114B, 116B) in the camera
network 100B through the wireless communication network 110B. The
cameras 102B, 104B, 106B may be coupled with the electronic modules
112B, 114B, 116B through preferably a wired connection, or
alternatively, a wireless connection.
[0064] Unlike in the embodiment of FIG. 1A, the controller 108B in
the camera system 100B of FIG. 1B is arranged to communicate with
only one of the cameras 106B in the camera network 100B. In this
embodiment, the camera 106B in communication with the controller
108B serves as a `master` camera (the camera with a mark `m` on the
body) for controlling and synchronizing the operation of the
cameras 102B, 104B, 106B in the camera network. Preferably, the
`master` camera 106B is operable to synchronize the time base
and/or the frame rate and reduce the frame offset (difference
between frame start times of different cameras) of the cameras
102B, 104B, 106B to realize simultaneous synchronized operation of
the cameras in the camera network 100B. In the present embodiment,
the synchronization of the time base refers to the minimization of
differences in the time base of different cameras 102B, 104B, 106B
in the camera system 100B. On the other hand, the reduction in
frame offset among the cameras 102B, 104B, 106B in the camera
system 1008 is realized by a continuous adjustment of the frame
rate of the cameras. An administrator of the camera network 1008
can control the activation, synchronization and operation of the
cameras 102B, 104B, 106B in the camera network 100B through the
controller 108B as well as the `master` camera 1068. In this
embodiment, the time base of each of the cameras 1028, 104B, 106B
are synchronized to the time base of the `master` camera 106B,
whereas the frame offset in the camera system 1008 is minimized by
adjustment of the frame rates of the cameras 1028, 1048 in the
camera system.
[0065] FIG. 1C shows yet another camera network 100C in accordance
with one embodiment of the present invention. In this embodiment,
the camera network 100C includes three cameras 102C, 104C, 106C.
The cameras 102C, 104C, 106C in the camera system 100C, which may
have their operation characteristics/parameters originally out of
synchronization due to the differences caused by their internal
components such as the clock, are arranged to capture still or
moving images (and/or sound) simultaneously in a synchronized
manner, using the method provided in the present invention. Each of
the cameras 102C, 104C, 106C is equipped with necessary optical and
electrical components for capturing still or moving images and/or
sound. As shown in FIG. 1C, each camera 102C, 104C, 106C is further
coupled with an electronic module 112C, 114C, 116C having at least
one communication means for enabling communication with other
cameras 102C, 104C, 106C in the camera network 100C through a
wireless communication network 110C. The cameras 102C, 104C, 106C
may be coupled with the electronic modules 112C, 114C, 116C through
preferably a wired connection, or alternatively a wireless
connection.
[0066] Unlike in the embodiments of FIGS. 1A and 1B, the camera
network 100C in FIG. 1C does not have any controllers. In this
embodiment, one of the cameras 106C serves as a `master` camera
(the camera with a mark `m` on the body) for controlling and
synchronizing the operation of the cameras 102C, 104C, 106C in the
camera network 100C. The electronic module 116C of the `master`
camera in this embodiment further includes a sensor arranged to
detect an external stimulus/event so as to trigger the activation,
operation and/or synchronization of the cameras 102C, 104C, 106C in
the camera system 100C. Preferably, the `master` camera 106C is
operable to synchronize the time base and/or the frame rate and
reduce the frame rate (difference between frame start times of
different cameras) of the cameras 102C, 104C, 106C to realize
simultaneous synchronized operation of the cameras in the camera
network 100C. In this embodiment, the time base of the cameras
102C, 104C are synchronized to the time base of the `master` camera
106C whereas the frame offset in the camera system 100C is
minimized by adjustment of the frame rates of the cameras 102C,
104C in the camera system, in a similar manner to that in the
embodiment of FIG. 1B.
[0067] Although the camera networks as shown in FIGS. 1A, 1B and 1C
all include three cameras and one controller, a person skilled in
the art would readily appreciate that the number of cameras and
controllers may be freely chosen, without deviating from the spirit
of the invention. Also, although the electrical modules are shown
to be separate components from the cameras in FIGS. 1A, 1B and 1C,
in some other embodiments, the electrical modules may be integrated
as an internal component of the cameras. In the present invention,
the cameras in the camera network may be of the same type or of
different types, for example, the cameras may be different
varieties of point and shoot cameras or single lens reflex
cameras.
[0068] FIG. 2 shows a block diagram 200 of the components of the
camera and of the electronic module coupled to the camera in
accordance with one embodiment of the present invention.
Preferably, the camera is coupled with the electronic module 212
through a wired connection, or alternatively, through a wireless
connection. In this embodiment, the camera 202 includes an imaging
module 220 arranged to capture still or moving image and/or sound.
Preferably, the imaging module 220 includes a number of optical and
electronic components such as display, control, lens, shutter,
clock etc. In addition, the camera 202 may also include an image
and video processor 222 arranged to process the captured image or
video. A storage module 224 may be provided in the camera for
storing the multimedia data obtained using the camera. In one
embodiment, the storage 224 may be provided by an external storage
media attachable to the camera, such as a USB, micro-USB, data
card, etc. Although not specifically shown, the camera may also
have other modules such as a communication module for enabling the
transfer of multimedia data, for example, to a server through a
wireless network or to a computer through a wired connection.
[0069] Also shown in FIG. 2 is the electronic module 212 coupled to
the camera 202 through a communication link 250 for enabling
communication of the camera 202 with other electronic modules,
cameras and/or controllers in a camera system, or other external
electronic devices. In one embodiment, a number of communication
links may be established at a time to enable simultaneous
communication with a number of different electronic devices.
Preferably, a communication module 226 is provided in the
electronic module 212 and the communication module is operable to
communicate wireless communication signals, such as WiFi and
Bluetooth signals, or other electromagnetic or optical signals with
the other electronic modules, cameras and/or controllers in a
camera system. The electronic module 212 may also include a
processor 228 for processing information arranged to synchronize
the cameras in a camera network. In one embodiment, the processor
228 may be arranged to process signals, data or operation
parameters such as time base and frame signals received from other
electronic modules, cameras and/or controllers in the camera
system, and/or to control the local operation parameters such as
time base and frame rate of the camera of which it is attached
to.
[0070] A memory module 230 may be provided in the electronic module
212 for storing communication or processed signals, data and
information. In one embodiment, the memory module for the
electronic module coupled to the `master` camera may store a list
containing information related to the cameras in the camera
network. This information may be, for example, a camera identifier
for each camera, together with a log of entries or operation
parameters or communication information of each of the cameras. In
some embodiments, electronic module 212 may further include a
sensing module 232 arranged to detect an external stimulus/event so
as to trigger the operation of the camera 220 and/or the
synchronization and control of the cameras. For example, the
sensing module 232 may be a tactile sensor, a light sensor, an
electromagnetic signal sensor, an audio signal sensor arranged to
detect force, light, EM signals, audible signals, etc.
[0071] In the present description, for simplicity, the term
`camera` may refer to a camera itself or may refer to a camera
coupled with an electronic module as shown in FIG. 2.
[0072] Preferably, the electronic module 230 in FIG. 2 is arranged
to communicate with an external electronic device such as an
information processing system. Examples of such information
processing system include a computer, a tablet, a PDA, or
preferably, a mobile phone. In one example, the information
processing system comprises suitable hardware or software
components necessary to receive, store and execute appropriate
computer instructions. The components may include a processing
unit, read-only memory (ROM), random access memory (RAM),
input/output devices, input device, display means, sensors, control
means and communications links. The information processing system
may include instructions that may be included in ROM, RAM or disk
drives and may be executed by the processing unit. A plurality of
communication links may be provided for the information processing
system for connecting to one or ore electronic modules (or cameras)
in a camera network.
[0073] It should be noted that one or more of the functional
modules in the electronic module as shown in FIG. 2 may be
integrated with the camera. In other words, the electronic module
may have additional components or may be some of the components
removed; whilst the camera may have additional components/modules
for operation of the camera in the camera network. In one example,
all functional modules in the electronic modules are integrated
with the camera such that the cameras do not require an additional
electronic module.
[0074] FIG. 3 shows a block diagram 300 of the components of the
controller 308 in the camera network in accordance with one
embodiment of the present invention. In one embodiment, the
controller 308 includes a communication module 310 arranged to
enable communication with electronic modules coupled with the
cameras, and/or controllers in the camera system. Preferably, the
communication module 310 is operable to communicate wireless
communication signals, such as WiFi and Bluetooth signals, or other
electromagnetic or optical signals with the other electronic
modules, cameras and/or controllers in the camera system. The
controller 308 may also include a processor 312 for processing
information that is used to synchronize the cameras in the camera
network. In one embodiment, the processor 312 may be arranged to
process signals, data or operation parameters received from
electronic modules coupled with the cameras, and/or controllers in
the camera system.
[0075] A memory module 314 may be provided in the controller 308
for storing communication or processed signals, data and
information. Preferably, the memory module 314 may store a list
containing information related to the cameras in the camera
network. This information may be, for example, camera identifiers
for each camera, together with a log of entries or operation
parameters or communication information of each of the cameras in
the camera network. A control and display means 316 may be provided
in the controller 308 for facilitating an administrator of the
camera network to interact with the controller 308 and hence the
operation, synchronization, and initiation of the cameras in the
camera network. The control and display means 316 may include a
display screen with or without touch sensors, and/or control
buttons.
[0076] In one embodiment, the controller may be an information
processing system, such as a mobile phone, a desktop computer, a
laptop computer, a PDA, or a tablet, having operable processing,
memory, input/output, and/or display means with various software
and hardware architectures for enabling communication with the
cameras (and/or the electronic module coupled thereto) and for
controlling/synchronizing the operation of cameras in the camera
system.
[0077] As shown in FIG. 4, there is provided a method for operating
a camera network having a plurality of cameras, comprising the
steps of: communicating with the plurality of cameras to determine
one or more operation parameters for each of the plurality of
cameras; synchronizing the one or more operation parameters for
each of the plurality of cameras; and coordinating a capture of
multimedia data using the plurality of cameras with the one or more
synchronized operation parameters.
[0078] FIG. 4 shows the basic operation flow 400 of the camera
networks of FIGS. 1A, 1B and 1C. In one embodiment, the camera
networks of FIGS. 1A, 1B and 1C operates by first determining the
operation parameters including the time base and frame rate of the
cameras in the camera network in step (402). Upon determining the
time base and frame rate of the cameras in the camera network,
different time bases of different cameras are synchronized with
each other whereas different frame rates of different cameras are
adjusted or "synchronized" so as to minimize the frame offset among
the cameras in step (404). In one embodiment, this process involves
synchronizing the time base and frame rate of each camera to a
reference time base and a reference frame rate, which may be a time
base and frame rate set in the controller (in the embodiment of
FIG. 1A); or may be the time base and frame rate of one of the
camera, the `master` camera (in the embodiments of FIGS. 1B and
1C). Once the synchronization process in completed, the cameras
with the time bases synchronized, and the frame offset minimized,
are ready for capturing multimedia data such as still or moving
images and/or sound. As shown in step (406), this then involves
coordinating the capture or multimedia data using the synchronized
cameras. In one embodiment, the initiation of the capturing of
multimedia data is coordinated by the controller (in the embodiment
of FIG. 1A) or alternatively, by the `master` camera (in the
embodiments of FIGS. 1B and 1C). The controller or the `master`
camera may transmit a triggering signal with a triggering time code
to the cameras in the camera network to initiate the multimedia
capture process, based on the distance between the controller on
the `master` camera and the cameras in the camera network. In some
other embodiments, the `master` camera may be responsive to an
external triggering event that initiates the multimedia capture
process. Exemplary triggering events include a tactile signal, an
infrared signal, an electromagnetic signal, a light signal, or an
audible signal received at the `master` camera. During the
multimedia capturing process, the controller or the `master` camera
is arranged to monitor, coordinate and/or adjust the frame rate and
time base of the cameras in the camera network such that the time
base of different cameras remain synchronized and the frame offset
of the cameras is minimized during the multimedia capturing process
by continuously adjusting and synchronizing the frame rate.
[0079] FIGS. 5A and 5B show the process 500A, 500B for
synchronizing the time base between the controller 108 and one of
the camera 102 (coupled with electronic module 112) in the camera
network (embodiment of FIG. 1A), and between the `master` camera
106 (coupled with electronic module 116) and one of the other
cameras 102 (coupled with electronic module 112) in the camera
network (embodiments of FIGS. 1B and 1C). Although only one camera
to be synchronized is shown in FIGS. 5A and 5B, a person skilled in
the art could readily appreciate that the controller 108 or the
`master` camera 106 is operable to repeat the time base
synchronization process for different cameras in the camera network
so as to synchronize the time base of each of the cameras in the
camera network.
[0080] Initially, the controller, the `master` camera, and the
other cameras in the camera network may have different time base
(e.g. clock time). This difference in time base may be due to
different clock crystals or other internal components used in
different cameras, but may be compensated through adjustments using
the processors of the cameras. In order to synchronize the time
base of camera 102 to that of the controller 108 or the `master`
camera 106, the controller 108 or the `master` camera 106 first
transmits a communication signal to camera 102 in step (502A,
502B). Camera 102, upon receiving the communication signal from the
controller 108 or the `master` camera 106, transmits a response
signal back to the controller 108 or the `master` camera 106 in
step (504A, 504B). Preferably, the communication signal and the
response signal include a time code and/or a camera identifier.
[0081] Upon receiving the response signal, the controller 108 or
the `master` camera 106 determines a difference between the time
for transmitting the communication signal and the time for
receiving the response signal. This may be performed by using the
time codes in the communication and response signals, or using the
time log in the controller 108 or the `master` camera 106.
Preferably, the controller 108 or the `master` camera 106 then
determines the time (one-way) required for a signal to be
transmitted from the controller 108 or the `master` camera 106 to
camera 102, i.e. the time difference between the time for
transmitting the communication signal and the time for receiving
the response signal divided by two. Optionally, the controller 108
or the `master` camera 106 may repeat the above determination
process to obtain an averaged time difference required to transmit
a signal from the controller 108 or the `master` camera 106 to
camera 102 for improved accuracy by transmitting and hence
receiving additional signals as shown in steps (506A, 506B; 508A,
508B). Although in the embodiments shown in FIGS. 5A and 5B, the
transmission and response signals are transmitted one at a time, in
other embodiments, a number of consecutive transmission signals may
be sent at a time from the controller 108 or the `master` camera
106 and a number of consecutive response signals may be received at
the controller 108 or the `master` camera 106.
[0082] In the present invention, the time difference may depend on
the nature of the transmission signal, the operation environment of
the camera network or the distance between the controller or the
`master` camera and the other camera, etc.
[0083] Based on the determined time difference/averaged time
difference, the controller 108 or the `master` camera 106 transmits
a time base synchronization signal with a time code and the time
difference/averaged time difference between the controller 108 or
the `master` camera 106 and camera 102, as shown in step (510A,
510B). In the embodiment of FIG. 5A, the controller 108 may select
the clock of one of the cameras as a reference, or alternatively,
may use its own clock as a reference. Upon receiving the time base
synchronization signal at camera 102, camera 102 adjusts its clock
time by setting its clock time based on the time code and the time
difference/averaged time difference received. Preferably, camera
102 adjusts its clock time to be a time determined by the sum of
the time in the time code and the time difference/averaged time
difference. In a preferred embodiment, the time base difference
after synchronization may be less than several milliseconds. For
example, the time code may be 1:00:30.08, and time difference may
be 10 ms. Camera 102, which may initially has a time code of
1:00:40.00, upon receiving the 1:00:30.08 time code and the 10 ms
time difference/averaged time difference from the controller 108 or
the `master` camera 106, adjusts its clock time to be 1:00:30.09
such that its clock time is synchronized with that of the
controller 108 or the `master` camera 106 (the controller 108 or
the `master` camera 106 would have frame rate time of 1:00:30.09 by
the time camera 102 adjusts its clock time).
[0084] FIG. 6 shows a flow diagram 600 illustrating the steps of
performing time base synchronization in the camera network in
accordance with one embodiment of the present invention. The
process begins with step (602), transmitting a communication signal
from the controller or the `master` camera to each of the cameras
in the cameras network. Then, in step (604), the controller or the
`master` camera detects the response signal from each of the
cameras. Based on these signals, the controller or the `master`
camera then determines a transmission time difference from the
controller or the `master` camera to each of the cameras in the
camera network, as shown in step (606). An averaged transmission
time difference may be determined in step (608) for improved
transmission time difference accuracy by repeating the time
difference measurements. Preferably, the controller or the `master`
camera maintains a list having operation parameters or data of each
of the cameras in the camera network (each having its own camera
identification code). In one embodiment, the controller or the
`master` camera may use their own time base as reference. However,
in another embodiment, the controller or the `master` camera may
use a time base of any one of the cameras in the camera network as
reference, and adjusts its own time base accordingly, without
deviating from the scope of the invention.
[0085] Once the transmission time difference/averaged transmission
time difference between the controller or the `master` camera and
each of the cameras in the camera network is determined, the
controller or the `master` camera, in step (610), transmits a
receptive time base synchronization signal having a time code, and
a respective determined transmission time difference/averaged
transmission time difference, to each of the cameras in the camera
network respectively. Then, each of the cameras in the camera
network, upon receiving the time base synchronization signal,
adjusts it local time base to substantially conform to that of the
controller or the `master` camera, as illustrated in step
(612).
[0086] FIGS. 7A and 7B show the process 700A, 700B for adjusting
and synchronizing the frame rate between the controller 108 and one
of the cameras 102 in the camera network (embodiment of FIG. 1A),
and/or between the `master` camera 106 and one of the other cameras
102 in the camera network (embodiments of FIGS. 1B and 1C), so as
to minimize the frame offset. Although only one camera 102 is shown
in FIGS. 5A and 5B, a person skilled in the art could readily
appreciate that the controller 108 or the `master` camera 106 is
operable to repeat the frame rate adjustment and synchronization
process for different cameras in the camera network so as to
minimize the frame offset among the cameras in the camera
network.
[0087] As shown in FIGS. 7A and 7B, the controller 108 or the
`master` camera 106 is arranged to transmit a frame start signal to
the other camera upon each frame initiation, as shown in steps
(702A, 702B; 704A, 704; 706A, 706B), where each step correspond to
one frame start signal transmission. For the embodiment of the
camera network utilizing the controller 108, the controller 108 may
be arranged to monitor the frame rate of at least one of cameras in
the camera network, and uses the frame rate of one of the camera as
a reference for the frame initiations. For the embodiment of the
`master` camera 106, the frame initiations at the `master` camera
itself are used.
[0088] Preferably, camera 102, upon receiving each frame start
signal, obtains a time code from its local system. This time code
is preferably time base synchronized with that of the controller
108 or the `master` camera 106 based on the time base
synchronization process described with respect to FIGS. 5A-6.
Alternatively, the frame start signal transmitted from the
controller 108 or the `master` camera 106 to camera 102 includes a
time code. In either case, camera 102 may include a log of time for
receiving of the frame start signals from the controller 108 or the
`master` camera 106. This enables camera 102 to determine a frame
rate based on the frame start signals received. In one embodiment,
a frame time difference may be determined based on the difference
in time code between two consecutive frame start signals. In other
embodiments, more than two consecutive frame start signals may be
used to obtain an averaged frame time difference.
[0089] Camera 102, upon determining the frame time difference,
compares the frame time difference with a local frame time
difference. If the comparison shows that the local frame time
difference is smaller than the determined frame time difference,
then camera 102 may gradually reduce its frame rate (increase frame
time difference) until the frame offset between camera 102 and the
controller 108 or the `master` camera 106 is substantially
minimized. Alternatively, if the comparison shows that the local
frame time difference is larger than the determined frame time
difference, then camera 102 may gradually increase its frame rate
(reduce frame time difference), until the frame offset between
camera 102 and the controller 108 or the `master` camera 106 is
substantially minimized. In either case, the end result would be
that the time difference between the frames of camera 102 and the
controller 108 or the `master` camera 106 will be close to zero,
i.e. the frame offset between the camera 102 and the controller 108
or the `master` camera 106 is minimized. In one embodiment, this
also means that the frame rates of the cameras are
synchronized.
[0090] Ideally, the frame rate of the camera 102 is considered to
be "synchronized" to the frame rate of the controller 106 (the
frame rate of the camera associate with the controller) or the
`master` camera 108 when the frame offset is exactly zero. However,
in one embodiment, the frame rate of the camera 102 is considered
to be synchronized to the frame rate of the controller 108 or the
`master` camera 106 when the difference in the frame rate (or the
frame time differences) is within a predetermined tolerance
difference range and the frame offset is close to zero within a
predetermined tolerance difference range. In other words, in this
embodiment, the frame rates of the cameras in the camera network
may be substantially but not necessarily exactly the same and there
may be some residue frame offset. In a preferred embodiment, under
any condition that the frame offset is beyond the tolerance
difference range, the frame rate synchronization process may be
repeated.
[0091] FIG. 8 shows a flow diagram 800 illustrating the steps of
performing frame rate adjustment and synchronization in the camera
network in accordance with one embodiment of the present invention.
The process begins with step (802), transmitting a frame start
signal from the controller or the `master` camera to each of the
cameras in the cameras network upon each frame initiation at the
`master` camera or camera associated with the controller. Each of
the cameras in the camera network then determines a frame time
difference based on at least two consecutive frame start signals
received from the `master` camera or the controller, as shown in
step (804). Upon determining the frame time difference indicative
of the frame rate of the `master` camera or the camera associated
with the controller, in step (806), each camera compares its local
frame time difference (i.e. local frame rate) with the determined
frame time difference (i.e. the frame rate of the `master` camera
or the camera associated with the controller). If it is determined
that the local frame rate at the respective camera deviates (higher
or lower) from the frame rate of the `master` camera or the camera
associated with the controller, the cameras adjusts its respective
frame rate so as to maintain the difference between the local frame
rate and the frame rate of the `master` camera or the camera
associated with the controller to be within a predetermined
tolerance range and hence to minimize the frame offset among the
cameras and the controller, as indicated in step (808). In one
embodiment, the cameras in the camera network may abruptly alter
their frame rate to conform to the frame rate of the `master`
camera 106 or the camera associated with the controller 108.
However, in an alternative embodiment, the cameras gradually adjust
their frame rate to conform to the frame rate of the `master`
camera 106 or the camera associated with the controller 108.
[0092] FIGS. 9A and 9B show the process for coordinating the
initiation and operation of the cameras in the camera networks of
FIGS. 1A, 1B and 1C for capturing multimedia data simultaneously in
a synchronous manner. Preferably, the cameras in the camera
networks have had their time base synchronized and their frame
offset minimized based on the methods illustrated in FIGS. 5A-8.
The controller 108 or the `master` camera 106 first sets up a
targeted initiation time for all cameras in the camera network
based on the determined transmission time difference (obtained
during time base synchronization) of the cameras. Specifically, the
controller 108 or the `master` camera 106 looks for the camera with
the maximum transmission time difference and determine a targeted
initiation time based on the maximum transmission time difference.
The targeting initiation time corresponds to the local time at the
controller 108 or the `master` camera 106 plus the maximum
transmission time difference. For example, the controller 108 or
the `master` camera 106 determines that the maximum transmission
time difference (for the camera that is furthest away) is 15
seconds and its local time is 2:02:25, it will calculate the
targeted initiation time to be 2:02:40.
[0093] Once the targeted initiation time is determined, the
controller 108 or the `master` camera 106 sends an initiation
command with the determined targeted initiation time to camera 102
(with maximum transmission time difference), as shown in step
(902A, 902B). As could be readily appreciated, preferably, the
controller 108 or the `master` camera 106 first sends the
initiation command to the camera with the largest transmission time
difference, then to the camera with the second largest transmission
time difference etc. In some cases, the controller 108 or the
`master` camera 106 may send the initiation command to the cameras
at the same time. Upon receiving the command, the cameras, with
their time base and frame rate synchronized, will wait for the
targeted initiation time and activate to capture multimedia data
simultaneously and synchronously.
[0094] During operation of the camera 102 for capturing multimedia
data, the controller 108 or the `master` camera 106 will continue
to synchronize the time base and/or reduce the frame offset of the
cameras in the camera network by dynamically adjusting the time
base and the frame rates of the cameras using the methods as shown
in FIGS. 5A-8, as shown in steps (904A, 904B; 906A, 906B).
[0095] FIG. 10 shows a flow diagram 1000 illustrating the steps of
coordinating the initiation and operation of the cameras in the
camera network in accordance with one embodiment of the present
invention. In one embodiment, a controller or a `master` camera is
arranged to determine a targeted initiation time for initiating the
cameras in the camera network. In one example, the controller or
the `master` camera may be arranged to receive a camera network
activation request from the user. Upon receiving such request, the
controller or the `master` camera determines a targeted initiation
time in step (1002) based on the maximum transmission time
difference, as discussed above. Then, the controller or the
`master` camera sends an initiation command with the targeted
initiation time to each of the cameras in the camera network in
step (1006). Upon receiving the initiation command, the cameras
wait for the targeted initiation time for activation to capture
multimedia data in a simultaneous and synchronous manner in step
(1010). During operation (capturing multimedia data), the
controller or the `master` camera dynamically (or periodically)
adjusts the time bases and frame rates of the cameras such that the
cameras remain synchronized at all time during operation, as
indicated in step (1012).
[0096] In an alternative embodiment, such as in the camera network
of FIG. 1C, the `master` camera is arranged to detect an external
triggering event indicative of an initiation request, as indicated
in step (1004). Preferably, the triggering event may be a tactile
signal, an infrared signal, an electromagnetic signal, a light
signal, or an audible signal received at the `master` camera (using
the sensor in the electronic module). Upon determining the
triggering event, the `master` camera calculates the targeted
initiation time based on the maximum transmission time difference.
Once the targeted initiation time is determined, the `master`
camera sends an initiation command with the targeted initiation
time to each of the cameras in the camera network in step (1008).
Upon receiving the initiation command, the cameras wait for the
targeted initiation time for activation to capture multimedia data
in a simultaneous and synchronous manner in step (1010). During
operation (capturing multimedia data), the `master` camera
dynamically (or periodically) adjusts the time bases and frame
rates of the cameras such that the cameras remain synchronized at
all time during operation, as indicated in step (1012).
[0097] The above description provides a number of different
embodiments of camera networks, cameras, electronic modules, time
base synchronization methods, frame rate synchronization methods,
and camera network initiation and coordination methods. A person
skilled in the art would readily appreciate that different
embodiments disclosed above may be used interchangeably or in any
combination, without departing from the spirit of the invention.
Also, although the above description only discloses methods for
synchronizing the time base and the minimization of the frame
offset by dynamic adjustment of the frame rates, it should be noted
that other types of operation parameters of the cameras may also be
synchronized using the method disclosed.
[0098] The system for realizing the synchronization and operation
of the cameras in the camera network may be arranged in the
controller, the `master` camera or the other cameras. In one
alternative embodiment, the system may be distributed in the
controller, the `master` camera or the other cameras.
[0099] The camera synchronization and operation methods and systems
in the present invention present a number of distinct advantages.
Firstly, the use of cameras (with an electronic module) operable to
communicate with each other or with a controller enables different
types of cameras to have their operation parameters synchronized.
This is particularly importantly for photographic applications
(photo/video) which require more than one camera in operation at
the same time. By dynamically adjusting the frame rate and time
base of the cameras, the cameras may remain synchronized at all
times (time base synchronized and frame offset minimized).
Furthermore, the embodiment which allows for detection of
triggering event for activating the cameras in the camera network
enables a fully automated operation of the cameras. The
synchronization and operation methods and systems disclosed
substantially eliminate the human factors such as response time for
pressing buttons from the system, thus enabling a more reliable and
robust camera operation network. Other advantages of the present
invention in terms of structure, function, cost-effectiveness, and
manufacture ease and costs will become apparent to those skilled in
the art, with reference to the specification.
[0100] It will be appreciated by persons skilled in the art that
numerous variations and/or modifications may be made to the
invention as shown in the specific embodiments without departing
from the spirit or scope of the invention as broadly described. The
present embodiments are, therefore, to be considered in all
respects as illustrative and not restrictive.
[0101] Any reference to prior art contained herein is not to be
taken as an admission that the information is common general
knowledge, unless otherwise indicated.
* * * * *